JP2014088508A - Resin-coated metallic pigment and coating composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin-coated metallic pigment having small color tone degradation such as metallic luster and concealment property by resin coating, and excellent adhesion property and chemical resistance.SOLUTION: A resin-coated metallic pigment has a coating layer containing a polymer between vinyl phosphonic acid and a monomer having 2 or more radical-polymerizable double bonds and/or an oligomer having 2 or more radical-polymerizable double bonds on the metallic pigment.

Description

  The present invention relates to a resin-coated metal pigment and a coating composition containing the same.

  Conventionally, metal pigments have been used for metallic paints, printing inks, plastics kneading, and the like for the purpose of obtaining a cosmetic effect that emphasizes a metallic feeling. However, an aluminum pigment that has not been subjected to any treatment on the surface has a high metal feeling and a high design property, but is inferior in adhesion to the resin of paint and printing ink. Therefore, when the adhesion test by cellophane tape peeling is performed, there is a drawback that a large amount is peeled off, and there is also a drawback that there is no protective function against chemicals.

  This is presumably because the compatibility and wettability of the aluminum pigment surface with the paint and printing ink resin are insufficient. As an improvement measure, a method of performing a surface treatment of an aluminum pigment has been proposed.

  In Patent Document 1, a flaky aluminum powder, which is an aluminum pigment, or a paste of flaky aluminum powder is dispersed in an organic solvent, and first, a radical polymerizable unsaturated carboxylic acid or the like is adsorbed on the surface, and then a radical polymerizable second powder. A method of surface coating with a polymer produced from a monomer having 3 or more heavy bonds has been proposed.

  In Patent Document 2, a uniform and highly three-dimensionally crosslinked coating film is formed on the metal pigment in order to prevent the color tone of the resin-coated metal pigment from decreasing and further improve chemical resistance and weather resistance. A method has been proposed.

Japanese Patent Publication No. 1-449746 International Publication WO 96/38506

  However, in the method of Patent Document 1 whose main purpose is to realize chemical resistance of the metallic coating film, it is necessary to add a considerable amount of the monomer to be coated. It has the problem of being lowered. The method of Patent Document 2 also improves the metal feeling and design properties to some extent, but is insufficient compared to the color tone of a metal pigment that has not been subjected to surface coating treatment.

  The present invention has been made in view of the above-mentioned problems, and a resin-coated metal pigment having a low color tone deterioration such as metallic luster and concealment due to resin coating and having excellent adhesion and chemical resistance, and the same It aims at providing the coating composition containing this.

  As a result of intensive studies on the above problems, the present inventors have found that a metal pigment, vinylphosphonic acid, a monomer having two or more radically polymerizable double bonds, and / or 2 radically polymerizable double bonds. The inventors have found that a resin-coated metal pigment having excellent color tone, adhesion, and chemical resistance can be obtained by copolymerizing and coating an oligomer having at least one, and the present invention has been completed.

That is, the present invention is as follows.
[1]
A coating layer containing a polymer of vinylphosphonic acid and a monomer having two or more radical polymerizable double bonds and / or an oligomer having two or more radical polymerizable double bonds on a metal pigment; Resin-coated metal pigment.
[2]
The resin-coated metal pigment according to [1], wherein the metal pigment is an aluminum pigment.
[3]
A coating composition comprising the resin-coated metal pigment according to [1] or [2].

  According to the present invention, a resin-coated metal pigment having excellent color tone, adhesion, and chemical resistance, and a coating composition containing the same, with less deterioration in color tone such as metallic luster and concealment due to resin coating. Can do.

  DESCRIPTION OF EMBODIMENTS Hereinafter, a mode for carrying out the present invention (hereinafter referred to as “the present embodiment”) will be described in detail. However, the present invention is not limited to this, and various modifications can be made without departing from the gist thereof. Is possible.

[Resin-coated metal pigment]
The resin-coated metal pigment according to this embodiment includes a vinyl phosphonic acid, a monomer having two or more radical polymerizable double bonds and / or an oligomer having two or more radical polymerizable double bonds on the metal pigment. And a coating layer containing a polymerized product.

[Metal pigment]
Although it does not specifically limit as a metal pigment of this embodiment, Specifically, base metal powders, such as aluminum, zinc, iron, magnesium, copper, nickel, and those alloy powders are mentioned. Particularly preferred are aluminum powders that are frequently used as metallic pigments. As the aluminum powder used in the present embodiment, those having a surface property, a particle size, and a shape that satisfy characteristics required for a metallic pigment such as surface gloss, whiteness, and glitter are suitable. The shape may be various shapes such as a granular shape, a plate shape, a lump shape, and a scale shape. In order to give an excellent metallic feeling and luminance to the coating film, a scale shape is preferable. For example, those having a thickness in the range of 0.001 to 1 μm and having a length or width in the range of 1 to 100 μm are preferable. The aspect ratio is preferably in the range of 10 to 20,000. Here, the “aspect ratio” is a value obtained by dividing the average major axis of the scaly aluminum powder by the average thickness of the aluminum powder. Further, the purity of the aluminum powder is not particularly limited, but those used for coating are preferably 99.5% or more in purity. Moreover, the aluminum powder is usually marketed in a paste state, and it is preferable to use this.

(Coating layer)
The coating layer of this embodiment includes a polymer of vinylphosphonic acid and a monomer having two or more radical polymerizable double bonds and / or an oligomer having two or more radical polymerizable double bonds.

(Vinylphosphonic acid)
The content of vinylphosphonic acid varies depending on the type and characteristics of the metal pigment and the specific surface area, but is generally preferably 0.01 to 10 parts by mass, more preferably 0 to 100 parts by mass of the metal pigment. 0.01 parts by mass to 5 parts by mass. When the content is 0.01% by mass or more, the resin layer is sufficiently formed on the surface of the metal pigment and tends to be more excellent in adhesion. Moreover, it exists in the tendency for the remarkable fall of a color tone to be suppressed more because it is 10 mass% or less.

(Monomer having two or more radical polymerizable double bonds)
The monomer having two or more radical polymerizable double bonds is not particularly limited, and conventionally known monomers can be used. Specific examples include di-2-methacryloyloxyethyl phosphate, tri-2-methacryloyloxyethyl phosphate, di-2-acryloyloxyethyl phosphate, tri-2-acryloyloxyethyl phosphate, diallyl dibutylphosphonosuccinate. Diesters of phosphoric acid or phosphonic acid such as nate; 1,6-hexanediol diacrylate, 1,4-butadiol diacrylate, triethylene glycol diacrylate, ethylene glycol dimethacrylate, triethylene glycol dimethacrylate, neopentyl glycol di Methacrylate, trimethylolpropane triacrylate, tetramethylolpropane tetraacrylate, tetramethylolpropane methane triacrylate, trimethylolpropane triacrylate Tacrylate, tetramethylol methane trimethacrylate, di-trimethylolpropane tetraacrylate, pentaerythritol tetraacrylate, di-pentaerythritol hexaacrylate, di-pentaerythritol pentaacrylate, di-pentaerythritol pentaacrylate monopropionate, triacryl formal, etc. An unsaturated carboxylic acid ester; a cyclic unsaturated compound; an aromatic unsaturated compound such as divinylbenzene, cyclohexene vinyl monooxide, divinylbenzene monooxide, diallylbenzene, divinyldiphenyl; or fluorine, silicon, nitrogen, etc. Examples thereof include unsaturated compounds having a functional group contained therein. Monomers having two or more radically polymerizable double bonds may be used alone or in combination of two or more.

(Oligomer having two or more radical polymerizable double bonds)
The oligomer having two or more radically polymerizable double bonds in the molecule is not particularly limited. Specifically, epoxidized 1,2-polybutadiene, acrylic modified polyester, acrylic modified polyether, acrylic modified urethane, acrylic Examples thereof include modified epoxies and acrylic modified spirans. Oligomers having two or more radically polymerizable double bonds may be used alone or in combination of two or more.

  The content of the monomer having two or more radical polymerizable double bonds and / or the oligomer having two or more radical polymerizable double bonds in the present embodiment is 0 with respect to 100 parts by mass of the metal content of the metal pigment. It is preferable that it is 1 mass part-50 mass parts.

[Method for producing resin-coated metal pigment]
As a method for producing a resin-coated metal pigment, after dispersing metal pigment particles in an organic solvent, first adding vinylphosphonic acid, a monomer having two or more radical polymerizable double bonds in the molecule and / or Alternatively, a method in which an oligomer having two or more radically polymerizable double bonds is added, a polymerization initiator is further added to perform a polymerization reaction, and the resin is coated on the surface of the metal pigment particles is preferable. The polymerization reaction conditions are desirably 50 ° C. to 150 ° C. and 5 minutes to 12 hours. In order to increase the polymerization efficiency, it is desirable to perform polymerization in an inert gas atmosphere such as nitrogen or helium. At the end of the polymerization, the organic solvent may be filtered off, the non-volatile content may be adjusted to 20-80%, and other solvents, additives, etc. may be added as necessary to make a paste.

  The method for adding vinylphosphonic acid is not particularly limited, and a known method is used. A predetermined amount of vinylphosphonic acid may be added directly to the solvent in which the metal pigment is dispersed, or may be added after diluting with a suitable solvent. Alternatively, vinylphosphonic acid may be mixed with the metal pigment and then dispersed in the solvent.

  Examples of the polymerization initiator that can be used in the present embodiment include those generally known as radical generators. Such a polymerization initiator is not particularly limited. For example, peroxides such as benzoyl peroxide, lauroyl peroxide, bis- (4-t-butylcyclohexyl) peroxydicarbonate; and 2,2′- Examples include azo compounds such as azobis-isobutyronitrile and 2,2′-azobis-2,4-dimethylvaleronitrile. Although the usage-amount of a polymerization initiator is each adjusted with the reaction rate of a polymerizable monomer, it is not specifically limited, 0.1 mass part-25 mass parts are preferable with respect to 100 mass parts of metal pigments.

  The organic solvent used to disperse the metal pigment is not particularly limited as long as it is inert to the metal pigment. For example, aliphatic hydrocarbons such as hexane, heptane, octane, and mineral spirits; benzene, toluene, Aromatic hydrocarbons such as xylene and solvent naphtha; ethers such as tetrahydrofuran and diethyl ether; alcohols such as ethanol, 2-propanol and butanol; esters such as ethyl acetate and butyl acetate; glycols such as propylene glycol and ethylene glycol Glycol glycols such as propylene glycol monomethyl ether, propylene glycol monoethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether; propylene glycol monomethyl ether Seteto, propylene glycol monoethyl ether acetate, glycol esters such as ethylene glycol monomethyl ether acetate. These organic solvents may be used alone or in combination of two or more.

  The concentration of the metal pigment in the organic solvent is preferably 0.1 to 40% by mass, more preferably 1 to 35% by mass. In terms of efficiently performing resin coating on the metal pigment, the concentration of the metal pigment in the organic solvent is preferably 0.1% by mass or more. Moreover, it is preferable that the density | concentration of the metal pigment in an organic solvent is 40 mass% or less at the point which keeps the dispersion state of a metal pigment uniform.

[Use]
The resin-coated metal pigment of the present embodiment is suitable for automobiles, general household appliances, information household appliances typified by mobile phones, printing, metals such as iron and magnesium alloys, or coating of base materials such as plastics. Can be used and can exhibit high design properties.

[Coating composition]
The coating composition of this embodiment contains a resin-coated metal pigment. The coating composition is optionally used in the paint industry, such as pigments, dyes, wetting agents, dispersants, anti-splitting agents, leveling agents, slip agents, rheology control agents, viscosity modifiers, skins. Additives such as an anti-tension agent, an anti-gelling agent, an antifoaming agent thickener, an anti-sagging agent, an antifungal agent, an ultraviolet absorber, a film forming aid, and a surfactant can be further included as appropriate.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail with reference to an Example and a comparative example, this invention is not limited at all by the following examples. In the following description, “%” indicates mass%.

[Example 1]
In a 20 L reaction tank, 1500 g of aluminum paste (Asahi Kasei Chemicals Corporation, 0-2100 “average particle size 10 μm, nonvolatile content 74%”) and mineral spirit (manufactured by Shell Chemicals Japan, product name LAWS) 8300 g are used in the reaction tank. I put it in. And it stirred, introducing nitrogen gas, and raised the temperature in a system to 70 degreeC. Next, 8.3 g of vinylphosphonic acid was added and stirring was continued for 30 minutes.

  Next, a solution comprising 74.0 g of trimethylolpropane trimethacrylate, 33.0 g of di-trimethylolpropane tetraacrylate, 29.2 g of 2,2′-azobis-2,4-dimethylvaleronitrile, and 1200 g of mineral spirit was obtained. Produced. Then, this solution was added to the reaction vessel at a rate of about 7.9 g / min by a metering pump, and polymerization was carried out for a total of 6 hours while keeping the temperature in the system at 70 ° C. Sampling was conducted after the completion of the polymerization, and when the unreacted amount of trimethylolpropane trimethacrylate in the filtrate was analyzed by gas chromatography, 99% or more of the added amount had reacted. After completion of the polymerization, the mixture was naturally cooled, and the slurry was filtered to obtain a resin-coated metal pigment (aluminum paste). The non-volatile content of this paste according to JIS-K-5910 was 50.1% by mass.

[Comparative Example 1]
A resin-coated metal pigment (aluminum paste) was prepared in the same manner as in Example 1 except that acrylic acid was used instead of vinylphosphonic acid.

[Reference Example 1]
As Reference Example 1, uncoated aluminum paste (manufactured by Asahi Kasei Chemicals Corporation, 0-2100 “average particle size 10 μm, non-volatile content 74%”) was used for the following evaluation as it was.

[Evaluation 1 (Hiding property, dispersion state of resin-coated metal pigment)]
0.25 g of the resin-coated metal pigment obtained in Example 1 or Comparative Example 1 or the aluminum paste of Reference Example 1 as an aluminum component was weighed and manually using a micro spatula (30% butyl acetate, 45% toluene). %, Isopropyl alcohol 20% and ethyl cellosolve 5%). After visually confirming that there was no lump of the resin-coated metal pigment in the dispersion, one drop of the dispersion was dropped on the microglass cover using a pipette with a tip capillary and dried in an oven at 60 ° C. for 30 minutes. This sample was observed at a magnification of 3500 times using a digital microscope KH-7700 for the dispersion state of the metal pigment using an optical microscope.

Based on the observation results, the ratio (B) (A + B) between (A) the number of particle aggregate particles formed from two or more primary particles and (B) the number of non-aggregated primary particles was calculated as follows: evaluated. In addition, it is so favorable that a numerical value is large, and 0.3 or more is preferable practically. The evaluation results are shown in Table 1.
[Evaluation criteria]
◎: 0.9 or more ○: 0.6 or more and less than 0.9 △: 0.3 or more and less than 0.6 ×: less than 0.3

[Evaluation 2 (Evaluation of coating film adhesion, chemical resistance, gloss retention)]
5 g of the resin-coated metal pigment obtained in Example 1 or Comparative Example 1 or the aluminum paste of Reference Example 1 as an aluminum component was weighed and thinner (trade name “Plaace Thinner No. 2726” manufactured by Musashi Paint Co., Ltd.). 50 g and an acrylic resin (trade name “Plaace No. 7160” manufactured by Musashi Paint Co., Ltd.) 33 g were mixed to prepare a metallic paint.

  The metallic paint was applied to an ABS resin plate using an air spray device so that the dry film thickness was 20 μm, and dried in an oven at 60 ° C. for 30 minutes to obtain a coating plate for evaluation. Using the above-mentioned evaluation coating plate, adhesion, chemical resistance, and gloss retention were evaluated. The evaluation results are shown in Table 1.

(Coating film adhesion)
Using the coating plate for evaluation, cello tape (registered trademark: manufactured by Nichiban Co., Ltd., CT405AP-18) was adhered to the coating film, pulled at an angle of 45 degrees, and the degree of peeling of the metal pigment particles was visually observed. Depending on the observation results, the evaluation was as follows.
[Evaluation criteria]
○: No peeling △: Some peeling ×: With peeling

(Chemical resistance of coating film)
The lower half of the evaluation coating plate was immersed in a beaker containing a 2.5N NaOH aqueous solution and left at 23 ° C. for 24 hours. The coated plate after the test was washed with water and dried, and then the immersion part and the non-immersion part were measured according to the condition d (8-d method) of JIS-Z-8722 (1982), and JIS-Z-8730 (1980) The color difference ΔE was determined according to 6.3.2. Evaluation was performed as follows according to the value of the color difference ΔE. In addition, it is so favorable that a value is small.
[Evaluation criteria]
○: Less than 1.0 Δ: 1.0 or more and less than 2.0 ×: 2.0 or more

(Gloss retention rate of coating film)
A 60 degree gloss (incident angle and reflection angle was 60 degrees) was measured using a gloss meter (manufactured by Suga Test Instruments Co., Ltd., digital variable gloss meter UGV-5D). The measurement value of the 60 ° gloss of the evaluation coating plate of Example 1 and Comparative Example 1 is G ′, and the evaluation coating plate of Reference Example 1 prepared in the same manner using the aluminum powder not coated with the resin is 60 °. The gloss measurement value was G, and the gloss retention rate R was determined by the following equation.
R = (G ′ / G) × 100
Depending on the value of the gloss retention rate R, the evaluation was as follows. In addition, it is so favorable that a numerical value is large, and 70 or more are preferable practically.
[Evaluation criteria]
◎: 90 or more ○: Less than 90 to 80 or more △: Less than 80 to 70 or more ×: Less than 70

  The resin-coated metal pigment of the present invention can be suitably used for metallic paints, printing inks, and plastic kneading applications, and is excellent in adhesion and chemical resistance when formed into a coating film, and has little deterioration in color tone. It is highly usable as a paint for automobiles and home appliances.

Claims (3)

  A coating layer containing a polymer of vinylphosphonic acid and a monomer having two or more radical polymerizable double bonds and / or an oligomer having two or more radical polymerizable double bonds on a metal pigment. , Resin-coated metal pigments.   The resin-coated metal pigment according to claim 1, wherein the metal pigment is an aluminum pigment.   A coating composition comprising the resin-coated metal pigment according to claim 1.